*I Can access the forums, but as soon as I click on a topic, I get a 404 error*
This error is caused by an improper setting in the forums permalink refrence…
Check to see if the forum is on a sub-page by editing the forum page and checking the “Page Parent” … if the page parent is anything OTHER THAN “Main (none)” then you are in a sub-page.
in the FORUM menu under the Manage Forums->Admin tab:
Make sure the page slug is actually both The Parentpage slug followed by a forward slash and then the forum page slug.
When making any changes to the page slug or permalinks on the main site, always save options, then Update the permalinks under the Tools tab and save options a second time.
Example: Mysite .org has a SUPPORT section where the forums are under the support page the page slug should be: support/sf-forums
Once Admin has updated the page slug and the permalinks of the forums, all groups, forums, topics and posts should appear normally.